1. Field of the Invention
The present invention relates to a scroll compressor, which is mainly used in a refrigerating apparatus as well as in an air conditioning apparatus, for business use and also for home use.
2. Description of Prior Art
Conventionally, as a compressor for use in the refrigerating apparatus and air conditioning apparatus, there are already known various types, such as of a reciprocating type compressor, a rotary type compressor, etc., and they are applied to separately, depending upon the respective properties, such as a cost, performances, etc. Among of those, in particular, the scroll type compressor has been achieving a great growth or success due to the properties thereof, such as high efficiency, low noise, low vibration, etc.
With the compression mechanism applied into such the scroll type compressor, in which a fixed or stationary scroll and a rotary scroll are toothed with, each having a wing or fin in a form of a vortex curve, thereby forming a several number of compressing chambers between them, wherein those chambers are reduced in the volumes thereof with shifting or moving from a peripheral portion side communicated to a suction inlet for sucking coolant to an internal periphery communicated to a discharge outlet due to a rotating movement of the rotary scroll, thereby to discharge the compressed coolant from the discharge outlet.
The rotary scroll mentioned above is supported with the Oldham ring, not spinning around it""s axis but for performing gyrating movement, and this Oldham ring is supported by a frame so that it can be shifted for achieving the purpose of the support above-mentioned. Accordingly, the Oldham ring can be shifted or moved between both the frame and the rotary scroll.
In general, the scroll compressor is manufactured by forming the rotary scroll, the stationary scroll and the frame, each being made of cast iron, however the Oldham ring is formed from sintered alloy of iron group. This is because the Oldham ring and the rotary scroll are brought under the most severe sliding condition, therefore they are formed with a respective combination of different kinds of metals, each. Namely, the cast iron contains has high wear and abrasion resistance, inherently, because it contains graphite therein, while the sintered alloy of iron group contains a lot of holes or vacancies therein, therefore is inferior in the property of wear and abrasion resistance.
By the way, as the coolant has was used a specific flon R12 or a specific flon R22. Those specific flons, each being stable chemically comparing to sulfur disulfide or methylchroride which was used before, as well as be flammable, and nonpoisonous, therefore they were used widely as an ideal coolant, and for a long time.
However, in recent years, it is ascertained that those specific flons containing chlorine atoms in the molecular thereof causes destruction of the ozone layer, therefore an alternative flon is developed to be used in place thereof.
As the alternative flon having high practicability, there is listed up a coolant, such as HFC (Hydro Fluoro Carbon) containing no chlorine atom therein, for example in xe2x80x9cOil/Air Pressure Technology (""94.6)xe2x80x9d (issued by Japan Industry Publication, Co., Ltd.).
However, when using the alternative coolant, since it contains no chlorine atom therein, the coolant cannot be expected to show sufficient lubricant property therewith. Because of this, the sliding condition comes to be severe, and in particular, in a case where the rotary scroll and the frame, both being made of cast iron as mentioned above, are combined with the Oldham ring made of sintered alloy of iron group, directly, on a bare surface thereof as it is, abrasion can be easily caused at the sliding portion, therefore, there is a possibility that the life time of the supporting structure portion is reduced or shorten.
This is, because the sliding portions between the Oldham ring and both the rotary scroll and the frame in the supporting mechanism mentioned above is easily brought into a condition where a portion of the lubricant film on the boundary thereof is dried up or broken due to the low lubricant property of the coolant (hereinafter, xe2x80x9ca boundary lubrication condition), therefore adhesion can easily occurs due to the fact that both the portions or structures being lubricated on the boundary are made of the similar materials of the iron group, i.e., the cast iron and the sintered alloy of iron group.
In this manner, the reduction of the life time of the Oldham ring and the rotary scroll comes up to be a problem, especially in a case of a compressor of the closed-type, which is generally of maintenance free and is kept driven for a long life time, since the life time of the compressor as a whole is directly determined by the life time of the above-mentioned supporting mechanism portion, therefore there is a possibility that it cannot be applied to or endure with actual practice or use thereof.
Then, as an example of measure for dealing with such the abrasion on the supporting mechanism portion which is provided with that Oldham ring and with the rotary scroll and the frame, there is known a technology shown in Japanese Patent Laying-open No. Hei 10-82382 (1998).
This conventional technology is shown in FIG. 5, wherein a reference numeral 6 depicts or illustrates the Oldham ring, which is formed from the sintered alloy of iron group. A reference numeral 17 indicates a projection, which is provided for supporting the rotary scroll, not spinning around the axis thereof by itself. A reference numeral 22 indicates a steam processed layer, i.e., it is formed by conducting a steam process or a nitride gas softening process thereon, after machining the sliding surface on the projection 17. With the provision of the steam processed layer 22 which is formed, there can be obtained a change in quality on the sliding surface of the projection 17 into the property other than that of the metal, as well as the increase in hardness thereof, thereby improving the durability or resistance against wear and abrasion under the condition of the boundary lubrication.
However, with the conventional art shown by the Japanese Patent Laying-Open No. Hei 10-82382 (1998), since it is a socalled chemical process which is applied thereon, it is impossible to control or manage the thickness of the processed film layer of the projections with high accuracy, therefore there is still a possibility that a trouble occurs sometimes when the Oldhum ring is assembled with the rotary scroll and the frame, in particular, in insertion thereof into gutters or drains of the rotary scroll and the frame to be assembled with.
An object of the present invention, therefore, is to provided a scroll compressor having no such the problem, i.e., no such the reduction or shortening in the life time due to the supporting mechanism portion of the rotary scroll, with use of the alternative coolant which contains no chlorine therein, as well as to dissolve such the problem as mentioned in the above in the assembling thereof, caused due to the accuracy of the parts thereof, thereby obtaining the scroll type compressor having high efficiency in the manufacturing thereof.
The above-mentioned object, according to the present invention, is accomplished by a scroll compressor, into which as a coolant is applied a mixture coolant obtained by mixing at least one or more kinds selected from a group of hydro fluoro carbon, within a closed container thereof, comprising:
an electric motor;
a rotary scroll driven with said electric motor; and
a stationary scroll, whereby forming a scroll compression mechanism between said rotary scroll for compressing said coolant, wherein said scroll compression mechanism comprises:
Oldham ring for supporting said rotary scroll so that said rotary scroll perform a gyrating movement with respect to said stationary scroll without spinning around an axis thereof; and
a frame for supporting said Oldham ring in movable manner for purpose of achieving supporting of said rotary scroll mentioned above, wherein said Oldham ring is formed from sintered alloy of iron group, while said frame and said rotary scroll are formed from cast iron, and after treating a steam process thereon, a sliding surface of said Oldham ring is machined.
Further, according to the present invention, there is also provide the scroll compressor as defined in the above, wherein a projecting surface of said Oldham ring treated with the steam process is machined by means of an end mill.